Cleanup environments doc

- Use correct "Note" formatting so they render correctly
- reordered sections so Node is first
- Use "Node.js" consistently (it is a product name just like Nashorn)
- added/tweaked some of the text
- simplified the Java code so it doesn't hit the internet.

docs/09.3-environments.md

@@ -9,6 +9,27 @@ next: addons.html
 One of the great things about React is that it doesn't require the DOM as a dependency, which means it is possible to render a React application on the server and send the HTML markup down to the client. There are a few things that React expects, so this guide will help you get started in your preferred environment.
 
 
+## Node.js
+
+[Node.js](http://nodejs.org/) is a popular JavaScript runtime that comes with an extensive core library and support for installing packages from npm to expand on the basic functionality. As we've described elsewhere in the documentation, you can install `react` and `react-dom` from npm.
+
+Example:
+
+```js
+var React = require('react');
+var ReactDOMServer = require('react-dom/server');
+
+var element = React.createElement('div', null, 'Hello World!');
+console.log(ReactDOMServer.renderToString(element));
+```
+
+If you use JSX, you may want to pre-compile your components. Alternatively you may want to consider using [Babel's require hook](https://babeljs.io/docs/usage/require/) or [`babel-node`](https://babeljs.io/docs/usage/cli/#babel-node).
+
+> Note:
+>
+> Some versions of Node.js have an `Object.assign` implementation that does not preserve key order. This can cause errors when validating the markup, creating a warning that says "React attempted to reuse markup in a container but the checksum was invalid". If you run into this issue, you can override `Object.assign` to use a polyfill that preserves key order. For more details, see [Issue #6451](https://github.com/facebook/react/issues/6451).
+
+
 ## Nashorn
 
 Nashorn is a lightweight high-performance JavaScript runtime that runs within the JVM. React should run out of the box in Java 8+.
@@ -18,63 +39,37 @@ Example:
 ```java
 import java.io.IOException;
 import java.io.InputStream;
-import java.net.MalformedURLException;
-import java.net.URL;
+import java.io.FileReader;
 
 import javax.script.ScriptEngine;
 import javax.script.ScriptEngineManager;
 import javax.script.ScriptException;
 
-import org.apache.commons.io.IOUtils;  // https://commons.apache.org/proper/commons-io/download_io.cgi
-
 public class ReactRender
 {
   public static void main(String[] args) throws ScriptException, IOException {
     ScriptEngine nashorn = new ScriptEngineManager().getEngineByName("nashorn");
 
-    nashorn.eval(getScript("https://fb.me/react-15.0.1.js"));
-    nashorn.eval(getScript("https://fb.me/react-dom-server-15.0.1.js"));
-
-    System.out.println(nashorn.eval("ReactDOMServer.renderToString(React.createElement('div', {}, 'Hello World!'));"));
-  }
+    // These files can be downloaded as a part of the starter kit
+    // from https://facebook.github.io/react
+    nashorn.eval(new FileReader("path/to/react.js"));
+    nashorn.eval(new FileReader("path/to/react-dom-server.js"));
 
-  public static String getScript(String url) throws MalformedURLException, IOException {
-    InputStream stream = new URL(url).openStream();
-    try {
-      return IOUtils.toString(stream);
-    }
-    finally {
-      stream.close();
-    }
+    System.out.println(nashorn.eval(
+      "ReactDOMServer.renderToString(" +
+        "React.createElement('div', null, 'Hello World!')" +
+      ");"
+    ));
   }
 }
 ```
 
-If your application uses node modules, or you want to transform JSX in Nashorn, you will need to do some additional environment setup. The following resources may be helpful in getting you started:
+If your application uses npm packages, or you want to transform JSX in Nashorn, you will need to do some additional environment setup. The following resources may be helpful in getting you started:
 
  * [http://winterbe.com/posts/2015/02/16/isomorphic-react-webapps-on-the-jvm/](http://winterbe.com/posts/2015/02/16/isomorphic-react-webapps-on-the-jvm/)
  * [https://github.com/nodyn/jvm-npm](https://github.com/nodyn/jvm-npm)
  * [https://gist.github.com/aesteve/883e0fd33390451cb8eb](https://gist.github.com/aesteve/883e0fd33390451cb8eb)
 
->Note: Using Babel within Nashorn will require Java 8u72+, as update 72 fixed [JDK-8135190](https://bugs.openjdk.java.net/browse/JDK-8135190).
-
-
-
-## Node
-
-You can also use React within a node server-side environment.
-
-Example:
-
-```js
-var React = require('react');
-var ReactDOMServer = require('react-dom/server');
-
-var element = React.createElement('div', {}, 'Hello World!');
-console.log(ReactDOMServer.renderToString(element));
-```
-
->Note: Some versions of node have an `Object.assign` implementation that does not preserve key order. This can cause errors when validating the markup, creating a warning that says "React attempted to reuse markup in a container but the checksum was invalid". If you run into this issue, you can override `Object.assign` to use a polyfill that preserves key order. For more details, see [Issue #6451](https://github.com/facebook/react/issues/6451).
-
-
-
+> Note:
+>
+> Using Babel within Nashorn will require Java 8u72+, as update 72 fixed [JDK-8135190](https://bugs.openjdk.java.net/browse/JDK-8135190).